Added a plugin for easily generating <figure> and <figcaption> with images

.themes/classic/plugins/figure_tag.rb

@@ -0,0 +1,69 @@
+# Title: Simple Image Figure tag for Jekyll
+# Author: Brandon Mathis http://brandonmathis.com
+# Description: Easily output images in <figure> with an optional <figcaption> and class names.
+#
+# Syntax {% figure [class name(s)] url [caption text] %}
+#
+# Example:
+# {% figure left half http://site.com/images/ninja.png Ninja Attack! %}
+#
+# Output:
+# <figure class='left half'><img src="http://site.com/images/ninja.png"><figcaption>Ninja Attack!</figcaption></figure>
+#
+# Example 2 (image with caption)
+# {% figure /images/ninja.png Ninja Attack! %}
+#
+# Output:
+# <figure><img src="/images/ninja.png"><figcaption>Ninja Attack!</figcaption></figure>
+#
+# Example 3 (just an image with classes)
+# {% figure right /images/ninja.png %}
+#
+# Output:
+# <figure><img class="right" src="/images/ninja.png"></figure>
+#
+
+module Jekyll
+
+  class FigureImageTag < Liquid::Tag
+    ClassImgCaption = /(\S[\S\s]*)\s+(https?:\/\/|\/)(\S+)\s+(.+)/i
+    ClassImg = /(\S[\S\s]*)\s+(https?:\/\/|\/)(\S+)/i
+    ImgCaption = /^\s*(https?:\/\/|\/)(\S+)\s+(.+)/i
+    Img = /^\s*(https?:\/\/|\/)(\S+\s)/i
+
+    @img = nil
+    @caption = nil
+    @class = ''
+
+    def initialize(tag_name, markup, tokens)
+      if markup =~ ClassImgCaption
+        @class = $1
+        @img = $2 + $3
+        @caption = $4
+      elsif markup =~ ClassImg
+        @class = $1
+        @img = $2 + $3
+      elsif markup =~ ImgCaption
+        @img = $1 + $2
+        @caption = $3
+      elsif markup =~ Img
+        @img = $1 + $2
+      end
+      super
+    end
+
+    def render(context)
+      output = super
+      if @img
+        figure =  "<figure class='#{@class}'>"
+        figure += "<img src='#{@img}'>"
+        figure += "<figcaption>#{@caption}</figcaption>" if @caption
+        figure += "</figure>"
+      else
+        "Error processing input, expected syntax: {% figure [class name(s)] /url/to/image [caption] %}"
+      end
+    end
+  end
+end
+
+Liquid::Template.register_tag('figure', Jekyll::FigureImageTag)